Load Type Zinc Oxide And Several Other Oxide Structure Characterization

Supported ZnO/activated carbon composite material was prepared from waste catalyst by microwave heat-treatment in this project.This paper mainly discussed the application of Rietveld whole-pattern fitting method in polycrystalline diffraction on the changes of crystal structure parameters of supported-ZnO, and its impact on the degradation performance to formaldehyde and total volatile organic compounds (TVOC),the microscopic state of the samples was characterized by modern analysis instruments.Meanwhile, had a comparison of stability and accuracy in phase quantitative analysis of several compounds between the whole-pattern fitting method and the traditional K-value method.In the preparation of samples, microwave heating mechanism and activation process were explored. Take advantage of waste catalyst, in which zinc acetate had been uniformly loaded to activated carbon, supported-ZnO of different contents was obtained with the ablation of carbon and enrichment of zinc oxide in the microwave heating process.The influences of different heating temperatures between 500℃and 1000℃on the crystallization condition, degree of enrichment, surface state, particle size of zinc oxide and the hole size and micro-morphology of activated carbon were discussed. Results showed that after microwave treatment at 900℃for 2 hours, ZnO particles were enriched in the holes of activated carbon, had a best crystallization.The content of ZnO changed as temperature changed.There were differences in the hole size of activated carbon and particle size of ZnO. X-ray Photoelectron Spectroscopy(XPS) analysis showed that there're oxygen loss in the crystal lattice of zinc oxide.The degradation effect of supported ZnO/ activated carbon to formaldehyde and total volatile organic compounds (TVOC) was evident. Supported-ZnO with lattice defects played a major role in the degradation of formaldehyde, the greater amount of enrichment the greater rate of the degradation, samples treated at 900℃reached a degradation rate of 94% to formaldehyde; activated carbon mainly adsorbed TVOC, samples treated at 1000℃which had a great amount of carbon had a degradation rate of over 99% to TVOC. Common zinc oxide had no degradation effect to formaldehyde basically, ordinary activated carbon only had a certain adsorption of formaldehyde.Structural refinement of supported-ZnO was carried through Rietveld whole-pattern fitting method. Results showed that atom occupation had changed, structural parameters deviated from the standard values, crystal lattice had certain defects. Lattice constant a and c of ZnO was larger than the initial model, axial ratio (c:a) continued to decrease. When the temperature increased from 700℃to 900℃, the lattice defects had been partly repaired.Powder mixture samples which contained two-phase or three-phase of Al2O3,ZnO, and TiO2 were used to carry out quantitative calculation seven times with the whole-pattern fitting method and K-value method separately. Results showed that whole-pattern fitting method had a higher stability and accuracy than the K-value method. The maximum deviation of component content compared with the actual value reached 13.0% using the K-value method, and deviation values were more than 10% for three times, over 6.0% for five times. However, while using the whole-pattern fitting method to calculate, all deviation values were less than 6.0%, the smallest deviation was only 0.1%.